Topographic contour lines were first introduced for representation of the third dimension in 1729 by a Dutch surveyor

• A. British navigator
• B. Dutch surveyor
• C. French cartographer
• D. German engineer

Answer: (B)

Encoding elevation on a flat map with lines that connect points of equal height lets us read three-dimensional terrain in a two-dimensional drawing. These contour lines show how steep or gentle a slope is and reveal the shape of the land—valleys, ridges, and plateaus—more clearly than earlier methods like shading or hachures.

In 1729, a Dutch surveyor introduced this contour-line approach, marking a pivotal moment in mapmaking by providing a precise way to represent height and terrain form. Before this, relief was conveyed less exactingly, but contour lines let map readers infer elevations and gradients at a glance, which greatly aided planning, surveying, and engineering.

So, the Dutch surveyor is the best answer because the contour-line technique—linking equal elevations to depict three-dimensional relief on a two-dimensional map—originated with that contribution, distinguishing it from the other professions listed.